Safety device for the explosive head of a missile



Jan. 10, 1956 L. o. BERGSTROM ET AL 2,730,046

SAFETY DEVICE FOR THE EXPLOSIVE HEAD OF A MISSILE Filed Sept. 12, 1951 FIG. 2

a /vwy M L 5 E MW v E MWR um m S m VGM 9L T NRE A 1E D x BM W mm 0% s LY RR AA LK G F 2,730,046 2 SAFETY DEVICE FOR THE EXPLOSIVE HEAD OF A MISSILE Lars Oscar Bergstriim and Karl Erik Waldemar Hjclm, Bofors, Sweden, assignors to Aktiebolaget Bofors, Bofors, Sweden, a' corporation of Sweden Application September 12, 1951, Serial No. 246,222 Claims priority, application Sweden September 19, 1950 14 Claims. (cl; 162-41 This invention relates to detonating devices for the explosive or war heads of missiles, such as rockets, and more particularly to safety and control means for such detonating devices.

Rockets and related missiles intended for hellow charge effect are usually provided at both ends with a fuse magazine, each including adetonator and a charge. The fuse magazine at the top of the head is generally set off by means of a pin or needle device operable by a force exterior to the head. This pin or needle device, when actuated, sets off the detonator which, in turn, ignites its charge. This charge produces a jet flame which is conducted to the second fuse magazine at the opposite end of the head where it sets as the detonator of the second magazine which now ignites its charge which, in turn, sets off .the shaped explosive charge of the head proper.

With rockets and other missiles of the general type, above referred to, the problem arises of providing safety means which afford full protection during transportation and storage and which become automatically effective upon firing or launching of the missile.

Several designs dealing with thisproblem are already known. According to one well known arrangement, a blocking element is inserted between .the needle device and the fuse magazine at the top end of the explosive head. This blocking element is withdrawn from its blocking position by a suitable electric device. Current is supplied by means of a 2-w'ire cable connected to the rocket at the front end thereof and leading to a source of current placed apart from the rocket. The circuit for the electric device must be closed after the firing or launching of the missile to avoida possible premature bursting of the explosive head while still in the launching device. 7 p

As will be obvious, an arrangement of this type entails several potential causes of failure and danger and is also complicated. 1

One of the objects of the present invention is to provide novel and improved safety means associated with the magazine fuses of the explosive heads of rockets. and similar missiles, which means permit safe storage and transportation of the missiles, effectively prevent a premature detonation of the explosive charge of the head and ready the missile for detonation of the explosive head when the missile is launched. I

Another object of the invention is to provide safety means of the general type herein referred to which are simple and reliable, and do not require an auxiliary source Other and further objects, features and advantages of means, for instance a screw con nection.

2,730,046 vPatented Jan. 10, 1956 2 the invention will be point'ed out hereinafter and set forth in the appended claims forming part of the application. V I

In the accompanying drawings several now preferred embodiments, of the invention are shown by way of illustration and not by way of limitation.

In the drawings:

Fig. ,l is a sectional elevational view of the explosive head of a missile equipped with safety and control means according to the invention, and

Fig. 2 is a fragmentaryv sectional view of the fuse magazine at the bottom end of the explosive head equipped with a modification of the safety and control means according to the invention.

Referring first to Fig. l in detail, the explosive or war head of a rocket or similar missile shown thereon, comprises a casing composed of two sections 1 and 2 which are joined for instance by screwing. Each end of the casing is provided with a fuse magazine. The magazine at the top comprises an actuator 3 including a needle or pin 3. This actuator, or more specifically the needle thereof, is actuated by an exterior force, for instance an impact, which serves to detonate a detonator 4 which, in turn, serves to ignite the charge 5 of the magazine. Neither the actuator 3 nor the fuse magazine proper is provided with any safety means.

As will be noted, a funnel shaped insert 6 forms two compartments within the casing of the head. The lower compartment 8 houses the shaped explosive charge of the head and the upper compartment 8 is left empty except for the component s r f the upper fuse magazine. An open cylindrical tube 7 leads from the apex of funnel 6 to the lower magazine. The tunnel and the tube may be made of any suitable material such as copper.

For the purpose of mounting the lower magazine in the explosive head, the bottom of easing section 1 is provided with a stepped axial bore. In this bore a tube or sleeve-shaped body 9 is inserted and secured therein, for instance by threading, into corresponding threads of easing section 1. As will be noted, tube 9 extends into the compartment 8 and is covered at .its inner end by a cover 11 having a central axial bore 12. Cover 11 is secured to tube 9 by any suitable means, for instance by threading. The entire portion of tube 9 extending into compartment 8 and cover 11 are covered with a cap 13 through which tube 7 is extended so that it communicates with bore 12. Tube 9 is providedwith an internal. radially protruding flange it) so as to form a central axial bore 14. This bore receives the cylindrical portion of a flanged insert 15. The upper end of the cylindrical portion of the insert abuts against the lower side of cover 11 and the upper side of the flange of the insert abuts against the lower side of the flange 10 of tube 5. The outer diameter of the flange of insert 15 corresponds to the inner diameter of tube 9 below flange It) so that the position of insert 15 is fixed within tube 9 The lower side of the flange of insert 15 is preferably concavely shaped and formstogether with the upper side of a second insert 16 a chambered. Insert 16 is secured Within the open lower' end of tube 9 by any suitable A diaphragm 17, for instance in forrnof a thin flexible circular disc,

is fitted between the two inserts 15 and 16. The diameter. of this disc is somewhat larger than .theinner diameter of the respective portion of tube 9 so that the disc is flexed into the illustrated convex position. As will-be noted, the diaphragm subdivides chamber 40 into two compartments. The upper side of insert 16 which bounds the lower compartment is provided with a recess in which is fitted an auxiliary charge 18 adapted ,to be ignited by a detonator 19 also disposed within insert 16.

The insert 16 is shown as a closed body but it is also possible to provide an open ring in which case the auxiliary charge 18 and its detonator 19 may be omitted.

Insert 15 is provided with a centrail axial bore 20 which issues into the bore 12. Bore 20 serves to receive slidably a pin 21, the lower end of which abuts against the upper side of diaphragm disc 17. The upper portion of the pin is provided with a transverse bore or recess in which is fitted a detonator 23 which coacts with a charge 24. Detonator 23 is intended to ignite charge 24 which, in turn, serves to ignite a larger charge 25 in the lower fuse magazine, which charge 25 finally serves to ignite the explosive charge in compartment 8.

When diaphragm disc 17 is in the illustrated convexly flexed position, detonator 23 is spaced apart from charge 24 so that the detonator is incapable of igniting charge 24. However, when the diaphragm disc is concavely flexed, that is, when the diaphragm nests itself into the curved lower surface of insert 15, the detonator 23 is in registry with charge 24 and is now capable of igniting the same.

Pin 21 is preferably provided with an axially elongated groove which is engaged by a cylindrical or spherical body 22 which is held in position by a corresponding groove in the inner wall of insert 15 defining bore 26. This body 22 which is preferably made of fireproof material serves to prevent a rotation of pin 21 which may move detonator 23 out of alignment with charge 24. Body 22 also shields detonator 23 against heat transmitted through tube 7 as long as the detonator is below body 22 as is illustrated.

For an understanding of the function of the arrangement, as hereinbefore described, two situations should be considered, namely, when the rocket is transported or in storage and when the rocket has been fired.

Referring first to the first mentioned situation, let it be assumed that the actuator 3 has been actuated by some accidental or unintentional cause. Then, detonator 4 ignites charge 5. As a result, a flame and a jet are created in the explosive head which willshoot down through tube 7 and bores 12 and 20 until stopped by body 22. In case body 22 does not stop the flame or heat completely and detonator 23 is detonated, this detonator being separated from charge 24 cannot ignite this charge.

Consequently, an ignition of the charge of the upper fuse magazine during transportation or storage has no serious consequences but is limited to the upper magazine and at worst to a detonation of detonator 23.

Let it now be assumed that the rocket is launched. Then, the heat developed in the motor of the rocket will reach the auxiliary detonator 19 which will ignite the charge 18. As a result, a gas pressure is developed in the lower compartment of chamber 40. This gas pressure acts upon the lower side of the diaphragm disc and deflects the same into its concavely flexed position. The diaphragm will remain in this position due to its bias and also due to the gas pressure in chamber 40. As will be apparent from the previous description, pin 21 now supports detonator 23 in a position in which the detonator is in registry with charge 24 and above body 22. Consequently, an ignition of charge by actuator 3 will now set in motion the aforementioned chain reaction finally re sulting in an explosion of the explosive head. In case a ring-shaped insert 16 is employed, the gas pressure developed in therocket during the launching will act directly upon the diaphragm disc but such pressure may not be sufficient under all conditions to deflect the diaphragm in'which case the support pin 21 will remain in its illustrated safety position.

In the modification of the lower fuse magazine, as shown in Fig. 2, identical reference characters are employed to designate corresponding parts. 7

The insert of Fig. 1 is replaced by an insert 15' which is distinguished from insert 15 by being provided with an axial bore corresponding to bore 20 and a second bore 34 formed within a protrusion 27 of insert 15. This protrusion extends into the bore 20' and is in form of an inverted cap. As will be noted, bores 20' and 34 are in axial alignment but separated by the bottom of the cap 27. A substantially cylindrical body 28 having an axial bore 28 is slidably fitted upon cap 27. A recess in the upper portion of cylinder 28 houses detonator 23 which is in communication with bore 20' and hence cylinder 7 through a funnel shaped channel 32.

A loaded spring 31 within bore 28 serves to bias the cylinder 28 into a position in which detonator 23 and charge 24 are in alignment. An axial elongated groove 35 in the outer wall of cylinder 28 and a dog 33 in the wall of insert 15' serve to guide cylinder 28 so as to prevent a rotation thereof.

Cylinder 28 is held in its lower or safety position by a locking device. This device is shown as comprising two balls 29 and 30 disposed within cages formed by bores in the wall of cap 27 and extending into the inner wall of the bore 28 of cylinder 28. The balls are held in the locking positions by the upper end of a rod or pin 26, the lower end of which is secured to the diaphragm disc 17. As will be noted, the upper end of pin 26 is recessed at 36. Consequently, balls 29 and 30 will fall into recess 36 when pin 26 is lifted by a deflection of diaphragm 17 into its'upper concave position, thereby releasing cylinder 28 for an upward movement by the action of spring 31.

For the understanding of the invention, the aforementioned two situations again must be considered.

It will be evident from the previous explanation that an ignition of the charge 5 by an actuation of actuator 3 during transportation or storage of the rocket will be limited to a detonation of detonator 23 so that an explosion of the charge proper of the head is effectively prevented.

Let it now be assumed that the rocket is fired. As previously explained, a gas pressure and heat developed in the rocket during the launching operation will result in a deflection of the diaphragm disc into its upper position either by direct gas pressure or by gas pressure developed by the ignition of the charge 18. As a result, the upwardly moving pin 26 releases balls 29 and 30 which drop into the recess 36. Cylinder 28 is now free to be moved upwardly by spring 31 into the position in which detonator 23 and charge 24 are in registry so that the explosive head is armed. Actually, this last mentioned upward movement of cylinder 28 does not take place immediately. Due to the rapid acceleration of the rocket, the cyinder will remain in its lower position until the acceleration has subsided to a velocity at which spring 31 can overcome the counterforce of the acceleration.

While the invention has been described in detail with respect to certain now preferred examples and embodiments of the invention it will be understood by those skilled in the art after understanding the invention, that various changes and specifications may be made without departing from the spirit and scope of the invention, andit is intended, therefore, to cover all such changes and modifications in the appended claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A fuse magazine for detonating the charge of the explosive head of a missile of the rocket type, comprising charge means for setting off the charge of the explosive head, detonating means for igniting said charge means, support means supporting one of said means disposed axially movable in said explosive head, the other of said means being stationarily disposed within said explosive head, spring means coacting with said support means and biasing the same toward an axial position in which the charge means and the detonating means are in a positional relationship operative for detonating the charge means, releasable locking means coact'ing with the support means for releasably retaining the same in a position in which the charge means and the detonating means are in a relative position inoperative for the purpose aforesaid, said locking means including retaining elements and an axially movable retaining and release member retaining in one position the retaining elements and releasing the same in another position, and yieldable means disposed within said explosive head responsive to a physical magnitude developed and rendered effective upon a discharge of the missile, the said yieldable means supporting said retaining and release member and being biased into a, position in which the said member occupies its retaining position, the said physical magnitude moving the yieldable means into a position in which said retaining and release member occupies its release position thereby freeing the support means for the aforesaid action by said spring means, the said support means being disposed in a position in the explosive head in which the force of the initial linear acceleration experienced by the missile when in flight acts upon the support means in an axial direction opposite to the spring means for retarding displacement of the support means until the said force has decreased below the force of the spring action. a

2. A fuse magazine according to claim 1, wherein the said yieldable means comprise diaphragm means disposed within the explosive head and coacting with the support means for controlling the position of the latter in response to a deflection of the diaphragm means, said diaphragm means being biased into a position in which the detonating means are in a position relative to the charge means inoperative for igniting the latter, the said physical magnitude acting upon the yieldable means being a gas under pressure, and means applying the said gas to said diaphragm means for deflecting the latter into a position in which the detonating means are in a position relative to the charge means operativefor igniting the latter.

3. A fuse magazine as defined in claim 2, wherein said diaphragm means are peripherally held and biased to assume either one of two stable positions, one of said positions being one in which the detonating means and the charge means are in the inoperative positional relationship and the other the one in which the said two means are in the operative positional relationship, said gas pressure causing the diaphragm means to move from one position into the other.

4. A fuse magazine as defined in claim 2, in combination with shield means disposed within the fuse magazine and shielding the detonating means against heat when the said detonating means are in the inoperative positional relationship with the charge means.

5. A fuse magazine as defined in claim 1, wherein the said diaphragm means are biased to hold the locking means in said retaining position, deflection of the di aphragm means under gas pressure moving the said diaphragm means into a position releasing the locking means, whereby the support means are freed for action by the spring means upon subsiding of the force of acceleration initially retarding displacement of the support means.

6. An explosive head of the hollow charge type for a missile of the rocket type comprising in combination an elongated casing, an impact fuse situated at the tip of the casing, a second fuse situated at the opposite end thereof, conduit means connecting the impact fuse with the second fuse, each of said fuses including charge means and detonating means therefor, ignition of the charge means of the impact fuse effecting detonation of the detonating means of the second fuse by the passage of hot gases and flames through said conduit means and ignition of the charge of the second fuse detonating the explosive head, safety and control means associated with the second fuse and controlling the ignition of the charge of the said fuse by a detonation of the impact fuse, the said safety and control means comprising axially movable support means supporting one of the said means of the second fuse, the other of said means being stationarily disposed within the second fuse, spring means in the sec ond fuse coacting with said support means and biasing the latter toward an axial position in which the charge means and the detonating means of the second fuse are in a positional relationship operative for ignition of the second fuse by a detonation of the impact fuse, releaseable locking means retaining said support means in a position in which the charge means and the detonating means of the second fuse are in a positional relationship inoperative for an ignition of the second fuse upon a detonation of the impact fuse, said locking means including retaining elements and an axially movable retaining and release member retaining in one position the retaining elements and releasing the same in another position, yieldable means disposed within said casing, the said yieldable means supporting said retaining and release member and being biased into a position in which the said member occupies its retaining position, and means for applying a gas under pressure to said yieldable means for moving the same into a position in which the said retaining and release member occupies its release position thereby freeing the support means for the aforesaid action by said spring means, the said support means being disposed in a position in the second fuse in which the force of the initial linear acceleration experienced by a missile when in flight acts upon the support means in an axial direction opposite to the spring means for retarding displacement of the support means until the said force is decreased be low the force of the spring action.

'7. An explosive head as defined in claim 6, wherein the 'said means for applying the gas under pressure to the yieldable means are positioned at a portion of the explosive head exposed to the ,flow of gas developed during thelaunching of the missile.

8. An explosive head as defined in claim 6, wherein the charge of the second fuse is stationarily mounted therein, and wherein said support means support the detonator of the second fuse and are mounted slidably in the direction of the longitudinal axis of said casing relative to the said charge, and wherein said yieldable means bias the support means into a position in which the detonator of the second fuse is spaced apart from the respective charge, thereby preventing ignition of the charge of the second fuse by detonation of the detonator of the said fuse.

9. An explosive head as defined in claim 6, wherein said yieldable means comprise diaphragm means peripherally held within said second fuse and coacting with the support means for control of the position of the latter, said diaphragm means being biased into a deflected position in which the support means hold the detonator supported thereon spaced apart from the respective charge and movable into another deflected position in which the support means are caused to move the detonator sup ported by it into juxtaposition wtih the respective charge.

10. An explosive head as defined in claim 9, wherein said diaphragm means are in form of a flexible disc abutting against said support means, and wherein said second fuse includes a chamber in which said disc is peripherally held so as to form two compartments therein, and wherein said gas under pressure is directed into one of said compartments, thereby causing a deflection of the disc for moving the support means into the position in which the detonator and the charge of the second fuse are in a relative position operative for ignition of the said fuse for the purpose of setting off said explosive head.

11. An explosive head as defined in claim 10, wherein an auxiliary detonator and charge are provided within said second fuse, said auxiliary charge communicating with one of said compartments so as to build up gas pressure therein for deflecting said diaphragm disc in response to the ignition of the said auxiliary charge, and said auxiliary detonator being adapted and positioned to be detonated by the heat generated during the launching of the missile.

12. An explosive head as defined in claim 6, wherein said support means comprise a sleeve axially slidable within said casing, the said spring means biasing the said sleeve toward the tip of the casing, and wherein the said retaining elements of the locking means are engageable with said support sleeve and a stationary wall portion within the casing, the said retaining elements being retained in said position of engagement by the retaining and release member in the retaining position of the looking means, movement of the said member together with the yieldable means releasing the retaining elements from said position of engagement whereby the support sleeve is movable by the spring means upon a decrease of the force of acceleration acting upon the support sleeve during the flight of the missile below the pressure exerted by the spring means.

13. An explosive head of the hollow charge type for a missile of the rocket type comprising in combination an elongated closed casing, an impact fuse situated at the tip of the casing, a second fuse situated at the opposite end thereof, conduit means connecting the impact fuse with the second fuse, each of said fuses including charge means and detonating means therefor, ignition of the charge means of the impact fuse effecting detonation of the detonating means of the second fuse upon passage of hot gases and flames through said conduit means, and ignition of the charge of the second fuse detonating the explosive head, and safety and control means associated with the second fuse and controlling the ignition of the charge of the said fuse by a' detonation of the impact fuse, the said safety and control means comprising axially movable support means supporting the detonating means of the second fuse in a position exposed to gases and flames passing through said conduit means, the charge means of the second fuse being stationarily disposed within the same protected from said gases and flames, the said support means being movable between an operational position in which the respective charge means are activated by the ignition of the respective detonating means and an inoperative position in which ignition of the said detonating means is without eflcct upon the said charge means, a diaphragm means within the casing controlling the position of said support means, the said diaphragm means being biased into a position in which said support means are in the inoperative position, the said diaphragm means defining a closed compartment within said casing and means developing gas pressure within said compartment upon exposure to the heat generated by the firing of the missile, the said gas pressure causing a deflection of the diaphragm means into a position in which the support means are moved into the operative position.

14. An explosive head according to claim 13, wherein the said diaphragm means support the support means for movement in unison therewith, the said diaphragm means movingthe support means into the operative position in response to a deflection of the diaphragm means by said gas pressure.

References Cited in the file of this patent UNITED STATES PATENTS 2,030,085 Woodberry Feb. 11, 1936 2,118,062 Woodberry May 24, 1938 2,145,507 Denoix Jan. 31, 1939 2,335,842 Nichols Nov. 30, 1943 2,469,352 Lauritsen May 10, 1949 FOREIGN PATENTS 694,402 France Sept. 15, 1930 614,320 Great Britain Dec. 14, 1948 968,025 France Apr. 12, 1950 

